1. Field
Embodiments of the present invention relate to an engine ignition control apparatus. More particularly, the invention relates to an engine ignition control apparatus suitable, for example, for improving the start-up performance of an engine having an idle air control valve (IACV).
2. Description of the Related Art
A conventional engine control apparatus is provided with an IACV on a bypass passage bypassing a throttle valve and adjusts the amount of intake air during idle running by controlling the opening degree of the IACV when the throttle valve is fully closed. In the opening degree control of the IACV, the fully opened position of the IACV is learned at the start-up of the engine, and the amount of air flowing through the IACV is computed based on the fully opened position.
Accordingly, when the engine is started during the control to learn the fully opened position (during full-open initial processing), the amount of intake air becomes large, so that the engine speed increases.
In this respect, Japanese Patent Application Publication No. 2000-9008 proposes an IACV control apparatus that performs ignition retard control in order to suppress the increase in the engine speed, when the IACV is fully opened. More specifically, this IACV control apparatus performs the ignition retard control by selecting an ignition advance value for feedback control to adjust the engine speed to a target rotational speed, instead of selecting a normal ignition advance value for the time when the throttle valve is fully closed.
The conventional IACV control apparatus performs the feedback control of the engine speed, and therefore needs to set the retarded ignition timing by trial and error while checking conditions of the actual vehicle. These conditions might include an increase in the engine speed. Thus, the conventional IACV control apparatus requires a long setting time.
In a case where the feedback control is implemented by PID control, all the constants of the PID are determined experimentally, so that a confirmation test needs to be conducted several times. In addition, in a case where an advance amount for each level of the engine speed is set by table setting, a test for all the lattice points of the levels of engine speed need to be previously conducted in order to set the advance amount for each level of the engine speed.